From: Mel Gorman <mel@csn.ul.ie>
To: Shaohua Li <shaohua.li@intel.com>
Cc: Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm <linux-mm@kvack.org>,
"Chen, Tim C" <tim.c.chen@intel.com>,
Rik van Riel <riel@redhat.com>, "Shi, Alex" <alex.shi@intel.com>,
Andi Kleen <andi@firstfloor.org>
Subject: Re: too big min_free_kbytes
Date: Thu, 24 Feb 2011 09:57:27 +0000 [thread overview]
Message-ID: <20110224095727.GQ15652@csn.ul.ie> (raw)
In-Reply-To: <20110224095208.GP15652@csn.ul.ie>
On Thu, Feb 24, 2011 at 09:52:09AM +0000, Mel Gorman wrote:
> On Thu, Feb 24, 2011 at 04:08:47PM +0800, Shaohua Li wrote:
> > On Wed, 2011-02-23 at 22:45 +0800, Andrea Arcangeli wrote:
> > > On Wed, Feb 23, 2011 at 01:29:14PM +0800, Shaohua Li wrote:
> > > > Fixing it will let more people enable THP by default. but anyway we will
> > > > disable it now if the issue can't be fixed.
> > >
> > > Did you try what happens with transparent_hugepage=madvise? If that
> > > doesn't fix it, it's min_free_kbytes issue.
> > with madvise, the min_free_kbytes is still high (same as the 'always'
> > case).
>
> This high min_free_kbytes is expected and is not considered a bug as it's
> related to transparent hugepages being able to allocate huge pages for a
> long period of time. Essentially, it's a cost of using hugepages.
>
I should be clearer here. madvise|always sets a high min_free_kbytes by
this check
if (ret > 0 &&
(test_bit(TRANSPARENT_HUGEPAGE_FLAG,
&transparent_hugepage_flags) ||
test_bit(TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
&transparent_hugepage_flags)))
set_recommended_min_free_kbytes();
so I'd expect the new higher value for min_free_kbytes once THP was ever
expected to be used.
If this new value was still considered a bug, removing the call to
set_recommended_min_free_kbytes() would always use the lower value that
was used in older kernels. This would "fix" the bug but transparent hugepage
users would not get the pages they expected the longer the system was running.
This would be harder for ordinary users to catch.
--
Mel Gorman
SUSE Labs
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next prev parent reply other threads:[~2011-02-24 9:57 UTC|newest]
Thread overview: 52+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-01-24 3:56 Shaohua Li
2011-01-24 15:00 ` Andrea Arcangeli
2011-01-25 14:35 ` Mel Gorman
2011-01-26 14:17 ` Mel Gorman
2011-01-26 15:23 ` Mel Gorman
2011-01-26 15:42 ` Andrea Arcangeli
2011-01-26 16:36 ` Mel Gorman
2011-01-26 17:42 ` Mel Gorman
2011-01-27 13:40 ` Mel Gorman
2011-01-27 15:27 ` Andrea Arcangeli
2011-01-27 16:03 ` Mel Gorman
2011-01-27 18:52 ` Andrea Arcangeli
2011-01-27 20:33 ` Rik van Riel
2011-01-27 21:31 ` Mel Gorman
2011-01-27 23:18 ` Rik van Riel
2011-01-28 10:35 ` Mel Gorman
2011-01-28 16:28 ` Andrea Arcangeli
2011-01-28 16:46 ` Mel Gorman
2011-01-28 17:16 ` Rik van Riel
2011-01-28 17:46 ` Andrea Arcangeli
2011-01-28 18:03 ` Rik van Riel
2011-01-28 18:24 ` Andrea Arcangeli
2011-01-28 19:34 ` Rik van Riel
2011-01-28 19:45 ` Andrea Arcangeli
2011-01-28 20:55 ` Rik van Riel
2011-01-29 19:45 ` Andrea Arcangeli
2011-01-28 17:34 ` Andrea Arcangeli
2011-01-28 17:10 ` Rik van Riel
2011-02-03 2:58 ` Andrea Arcangeli
2011-02-03 13:15 ` Mel Gorman
2011-02-03 18:59 ` Andrea Arcangeli
2011-02-03 14:36 ` Rik van Riel
2011-02-03 19:11 ` Andrea Arcangeli
2011-02-12 1:28 ` Simon Kirby
2011-02-14 2:25 ` Shaohua Li
2011-02-22 14:25 ` Mel Gorman
2011-02-22 14:42 ` Andrea Arcangeli
2011-02-22 14:50 ` Mel Gorman
2011-02-22 14:54 ` Andrea Arcangeli
2011-02-22 16:04 ` Mel Gorman
2011-02-22 16:40 ` Rik van Riel
2011-02-23 5:29 ` Shaohua Li
2011-02-23 14:45 ` Andrea Arcangeli
2011-02-24 8:08 ` Shaohua Li
2011-02-24 9:52 ` Mel Gorman
2011-02-24 9:57 ` Mel Gorman [this message]
2011-02-24 14:27 ` Andrea Arcangeli
2011-02-24 14:04 ` Andrea Arcangeli
2011-02-25 0:51 ` Shaohua Li
2011-02-25 12:13 ` Mel Gorman
2011-02-12 9:48 ` alex shi
2011-02-22 14:24 ` Mel Gorman
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